Self-aligning piston and piston rod



Oct. 30, 1951 A. J. BENT SELF-ALIGMNG PIsToN AND PIsToN Ron Filed July 5, 1948 mm mum ATTORNEY Patented Oct. 30, 1951 SELF-ALIGNING PISTON AND I ISTON ROD Arthur J. Bent, Pittsburgh, Pa., assigner to Westinghouse Air Brake Company, a corporation of Pennsylvania Original application July 31, 1947, Serial No.

194s, serial No. 36,848

2 claims. 01; sos- 20) This invention relates to a self-aligning piston and piston rod assemblage particularly adapted for use in a variable load fluid pressure brake cylinder device of the type disclosed in my copending application, Serial No. 764,941, led July n 31, 1947, of which the present application is a division.

It is the prime object of the invention to provide an improved self-aligning piston and piston rod assemblage particularly adapted for use in a brake cylinder device of the type above referred to.

Other objects and advantages will be apparent from thefollowing more detailed description of the invention.

In the accompanying drawing, the single figure is adiagrammatic sectional view taken longitudinally through a brake cylinder device embodying the invention.

As shown in the drawing, the improved brake cylinder Ydevice comprises a hollow cylindrical casing I which may be cast of aluminum to reduce its weight to a minimum commensurate with Y strength, and which is closed at one end by a preferably integral pressure head 2. To the open end of the casing I is secured an annular pressure head 3 interposed between said casing and a cup-shaped non-pressure head 4 which are secured together by bolts (not shown). The heads 3 and 4 also are preferably formed of aluminum to reduce their weight. A brake cylinder piston assemblage 5 is slidably mounted in the casing I, and at one side thereofis vthe usual or a main pressure chamber 6 to which is connected a pipe 'I by Way of registering passages Il extending through removable littings 9 and III and centrally through the pressure head 2. The pipe 'I 'is adapted to be connected in turn to a uid pressure control valve device (notshown), such as the Well-known AB valve, to effect variations in pressure of fluid in the pressure chamber 6 for controlling and operating piston assemblage 5.

The piston assemblage 5 comprises a piston head I I which may be formed of drawn steel to reduce to a minimum the amount of machine work necessary to form it. This head is provided with a circular flat central portion and an annular portion encircling the flat central portion which annular portion is in the form of a portion of a sphere. An annular peripheral groove I2 is machined in the head Il for securing a resilient snap-on packing cup I3, disposed in the chamber E, to one face` of said head. The packing cup I3 is provided with anY annular U-shaped portion I4, which portion is o-pen to chamber 6 and which curves into ,slidableontact with the inner wall 764,941. Divided and this application July 3,

of the casing in such a manner that pressure'of fluid in said chamber acts thereon .to urge it into sealing engagement with saidwall for preventing leakage of fluid under pressure past the piston head. An annular substantially U-shaped metal ring l5 is interposed between the portion I4 of the packing cup I3 and one face of a radially projecting annular ange I6 attached to the piston head II. A portion of the ring I5 is curved to form a support for the back of portion I4 -of cup I3. A lubricating swab I1, in the form of a felt or similar ring encased in an expander ring, is disposed within the ring I5 and thereby secured to move with the piston head II in slidable contact with the casing wall to distribute and store lubricant thereon for a consider-able period of time. The outer peripheral edgeof the flange I6 attached to the piston head II is machined" to provide/an accurate t for slidable contact btween said head and the casing wall.

A hollow cylindrical member I8, disposed on the opposite side of the piston head I I, is secured adjacent its one end to said head for movement therewith by an annular baille member I9, and is slidably guided at its opposite end by a sleeve member 20 disposed in and secured to the non# pressure head 4. The annular baille member I9 is secured at its outer periphery by a continuous weld 2I, or other suitable means, to a face of the flange I6 of the piston head II, and the vmember I8, which projects through the member I9, is secured to the inner peripheral edge of said member I9 by means of a similar continuous weld 22, or the like. The member I9 for the major portion of its width is dished in the direction toward the piston head II for the purpose of imparting rigidity to said member.

An annular compensating pressure chamber 23 is dened by the outer cylindrical surface of member I8 and the inner surface of casing I between the annular baille member I9 and the annular pressure head 3. The chamber 23 is connected to a pipe 24 by way of registering passages 25 in thepressure head 3, the non-pressure head 4 and a removable tting 26. The pipe 24 is adapted to be connected to a novel relay valve device (not shown), described in the aforemenf tioned copending application, for effecting variations in the pressure of fluid in the chamber 23 in accordance with the degree of loading on the vehicle. Pressure of fluid in the chamber 23lacts on the annular area of the baille member I9, secured to the piston head II, in opposition to the force on said head caused by the pressure of fluid inthe usual pressure chamber 6, and since the pressure in said chamber 23 is varied in the manner as above described, the effective force delivered by said head for applying the brakes varies in accordance with the degree of loading. The welds 2| and 22 acting to secure member I8 to member I9, and member I9 to fpiston head II serve also 'to form a seal for preventing uid under pressure from escaping from the compensating pressure chamber 23 past the baille member I9. A resilient annular sealing ring 2-'I is vdisposed in a groove in the pressure head 3 for slidable engagement with the outerfsurface-ofmember I8 to prevent leakage of fluid lim'dcr pressure from chamber 23 past said head.

The sleeve member 20 is 4provided at'one end with an outwardly projecting annular flange 28 which is disposed coaxially with relation to the member I8 in a central counter-bore 29 in the non-pressure head 4. This counter-bore provides a shoulder 3U against which the ange 28 rests.V en annular ring l'member 3l is Ypressed into the counter-bore ,which member abuts the flange 2'8, holding 'sa-id flange 'rigidly sea-ted against the Ashoulder 3%, thereby removably securngtl'ife sleeve IYmember 26 'to the head 4. A lubricating swab 32 in Vthe 'form of an annular felt ring is mounted ina groove in member 31 for slidable engagement with theoiter surface of the memberIB.

Thesealing ring y(27 is provided with an Vouter flatedge portion which is clamped between 4the heads '3 'and l to allow for easy removal and insertion and van inner edge portion 33 is made U-"shaped in crosssection, similar to portion Sli of cup '13. The portionlSS op'ensgin 4the direction of the :chamber 23 so that -action of pressure of fluid `therein urges the yring v2'! into sealing engagement 'with them'einber "I '3. The linterior of the hollow cylindrical sleeve member I8 forms a non-pressure chamber 321 whichfo'pens into the interior of the lnoir-pressure headY `4. The `nonfmessure chamber -34 is constantlyj'open to""atmosphere 'through a breather port 35 inhead covered Yby an air strainer -3'6 oi curled ihair -or the ke. 'The strainer :it is disposed'in an opencupasliaped'retainer 37 secured to th'evhead 54 and 4encircling the port 3b. `'The port y3:5 is providedto permit free passage ofair into and out of the non-pressure chamb'crm'll upon reciprocation of the piston head II in 'the 'casing I, while the strainer overgsaid 'port is 'adapted to prevent dust and dirt -:from entering said chamber. lThe strainer 3E is npreferably mounted at Vthe lowerV Yside of the non-'pressure head 54 in order to avoid, Yinsofar as possible, free entrance of *diftandmoist-ure Eto Zsaid strainer.

A base member 38 is disposed within the -nonpressure chamber tiladjacent-to the piston bead 4'II. A ho-116W piston rod 35, di the fusua-l type, secured alt its one endby means-'of rivets toa bos'st attach'ed'to the member '33. 'The opposite 'end "of vrthejroizlfti extends th'rou'gih .and slidably guided within a tapered opening I in an end-wall '42 -i'n the non-pressure ihead 4. A push rod `f3 projects into the rod in the usual manner-and abutsa steelinsert s4 Icarriedfb'y Lie aluminum base member l'3 3.

The 'base member 33 -is arranged to movelwith the'pistonfhead II fcr'transmitting thrust tothe push rod t, 'and thence tothe 4brake `rrigging -ffor applying the 'brakes "('nct Ashown). Clearance is provided between the outerp'er'iphery foi the lbase member 38 land the inner '-ivall ofthe-member "i3 .so that "as said base moves `with fthe piston Vhead fi I Eit is ffre'e to adjust itself 'in a 'radial Fdr'ection to correct for any initial misalignment with the piston II and the member I8 and thereby prevent binding. The tapered opening 4I in the wall 42 allows the piston rod 39 attached to the base member 38 the necessary freedom for such adjustment. V g

The face of the base 'member 38 -is provided with an annular curved surface 45, which may be in the shape of a portion of a sphere, for slidable engagement with the corresponding curved surface of the piston 'head II. The central portion oi the member 3B encircled by the annular curved surface 45 is y'provided with la cavity 4B of larger diameter than the 4diameter of the central flat portion `of the -piston head II so that the surface d5 is allowed lfreedom for travel on said head II to provide :for the previously described radial adjustment.

ill retaining member 41 in the form of a thin hollow cylinder is spot-welded to the inner wall of fthe cylindrical 'member =I8. The member 41 is provided With'a plurality `of spaced-apart thin yieldable ngers ES which rare Zdefined Avby longitudinally extending slots cut in the member '41. The lingers '58 are bent into engagement with the member V38 and act to hold said member and piston head II together during removal :of the casing -I from the=non-pressure fhead 4. -For example, if inspection of the packing feup I3 is desired, the casing `I is unbolted from `the nonpressure head i and said .ca-sing --is lslipped off over the piston'assemblage 5 toexposesaid packing cup. A retaining ring I9 -in the usual form, secured to the outer end of piston rod'39 eprevents the `member -38 from moving in the :direction of the left-hand, .as viewed `in the drawing, and the retainer member -41 comprising :the fingers 48 anchors the member I8 and ,attached piston head iI to said ibase member -38 to ,prevent them from moving Withvthe casing.

The fingers G8 are exible `so that, whereas they lare of sufficient. strength to serve -to an*- chor the :piston head II to the base -member \38, they yield to allow Ysaid base to move radially during the previously described aligning adjustment. One fend of a compression return spring 59 seats yon the flexible llingers '48, `urging said lingers vinto contact With the member S8 and, in turn, urging said 'member into contact with the piston head Ii, so that once Ysaid member has -moved yto an adjusted Eposition With respect to said ypiston yhead it'willlbe held in the adjusted position -by friction 'and the yiel'dable clamping action of the Ispring 'and iingers, it being Vunderstood that Vthe :structure -is at all times 4automatically yadjustable lto prevent lany bending action 'on the movable parts Atof the piston assemblage.

'Thev'co'mpre'ssi'on return v"spring 5i] is 'provided to 'serve the Vusual'purpose'of returning the'piston assemblage /5 'to its -normal brake rreleased posi@ tion, 'as lshown 1in `the drawing, in :'eecting the releaseof `a brake'application. The y'spring 50 disposed in the non-pressure chamber 43:4 fencir-r cling'the piston rod '39 and Sis 'tapered 'to 'prevent it frcrn cooking Iasitis Iiurther compressed during trave'l "of the piston assemblage 5. The vv0ppos'iteend ofthe spring *5B lseats en .an .annular seat flange 5I attached to l'a sleeve 52 `which is slidably mounted lon the lpis'ton rod 39. An annular Vesha'ped "resilient porous .lter member 153 encircles Ithe rod 39 and isin'terpo'sed be'- tween 1a beveled face lof the liiange V'5I and I'a beveled shoulder 54 -ffoime'd in the end wall f4-2 encircling the tapered =`opening lll lin Vthe r`non@ pressure head 4. The lter member 53 is squeez- 51 and shoulder 54 into contact with the outer surface of the piston rod 39 and with the portion of wall 42 encircling the opening 4I so that any air entering through said opening which may be carrying dust or dirt must pass through the member 53 and thereby be filtered or cleaned.

Since the welds 2| and 22 serve to secure the baie member I9 to the piston head II and the cylindrical member I8 to said baffle, as well as serve to seal on the compensating pressure chamber 23 encircling the member I8 from the nonpressure chamber within said member I8, said welds may be pressure tested to prove their sealing qualities. It will be appreciated that means other than welding, such as brazing or soldering might be employed to serve the same purpose.

The sealing ring 21 cooperating with the outer Wall of cylindrical member I8 is protected from excessive wear due to abrasive action of dust and dirt by virtue of its location within the brake cylinder device into which no dust laden air is allowed to low, either directly or indirectly. The ring 21 is further protected from excessive wear by virtue of its cooperation with the member I8, which remains entirely enclosed within the casing of the brake cylinder device at all times and is not subjected to corrosive action of the elements, consequently the member IB presents clean smooth surface for slidable sealing contact with said ring.

While only one illustrative embodiment of the invention has been shown and described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A piston assemblage comprising a piston head, a sleeve member having one end abutting said head, an annular member encircling said ed, by action of the spring 50, between the iiange viding for slidable movement of the abutting end of said rod radially on said head.

2. A piston assemblage comprising a piston head, a sleeve member having one end abutting said head, an annular member encirclingsaid sleeve member and having an annular air tight securing joint with said sleeve member and also having an air tight securing joint with said head adjacent its periphery, a piston rod extending through said sleeve member into abutting relation with said head, the abutting surfaces of said head and rod being respectively concave and convex in sliding contact with each other, means attached to said sleeve member for retaining said rod in proximity to said head and providing for slidable movement of the abutting end of said rod radially on said head, and spring means arranged to bias said piston rod in the direction of said piston head.

ARTHUR J. BENT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Halfvarson Oct. 12, 

